In a known coupling between a tool head and a tool support, the tool support has a holding fixture or a recess, while the tool head is provided with a pin shank part. To connect the tool head to the tool support, the pin shank part is put coaxially into the holding fixture, and the two parts are braced against each other by two screws that run transverse to the longitudinal direction of the tool support (i.e, by a clamping bolt and a countersunk head bolt). Due to the fact that, in this arrangement, screw forces directed transverse to the longitudinal axis of the tool support are converted into clamping forces parallel to the longitudinal axis of the tool support, a complicated spatial state of tension is present at the connection point. Because of this, uniform distribution of tension over the contact surface is difficult to achieve. Further, the extent of the axially oriented clamping force cannot be determined, which means that a stripping of the screw connection or too little bracing can very easily occur. Additionally, to prevent a relative rotation between the tool support and the tool head, a further component in the form of an eccentrically placed positioning pin must be provided. Moreover, the multiplicity of components detracts from an economical use of the coupling.
The clamping bolt and the countersunk head bolt each lie in such a way on the surface of the tool support that, in operation (for example, during machining of a workpiece), they can come into contact with chips and other impurities. Because of this, they are subject to a relatively great abrasion. When fine chips or metal dust penetrate the thread sections of the screws, a reliable screw connection is no longer assured, and a destruction of the thread can occur.